Designing With Light
Chapter 6
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Angle of Incidence
Diffuse
Diffuser
Opaque
Direct Distribution
Direct Glare
Downlight
The angle between a ray of light striking a surface
and a line perpendicular to that surface.
A translucent piece of glass or plastic that shields
the light source in a fixture. The light transmitted
throughout the diffuser is redirected and
scattered.
Term describing dispersed light distribution.
Refers to the scattering or softening of light.
Describes light leaving a fixture and entering the
illuminated space without first bouncing off of any
architectural elements such as the ceiling or walls.
Describes a material through which light does not
pass.
A type of ceiling luminaire, usually recessed,
where the light is directed downward.
Glare produced by a direct view of light sources.
It is often the result of fixtures with inadequate
shielding.
Aiming Angle
Glare
General Lighting
Indirect
Interreflection
Reflectance
Reflected Glare
Refractor
The effect of brightness or differences in
brightness within the visual field sufficiently high
to cause annoyance, discomfort or loss of visual
performance.
The angle, measured in degrees, between
vertical and the centerline of the beam of light
illuminating an object.
A light distribution pattern or luminaire in which
all of the light is directed upward to bounce off of
the ceiling.
Lighting designed to provide a uniform level of
illuminance throughout an area, exclusive of any
provision for additional task-specific lighting
requirements.
The ratio of light reflected from a surface to the
light incident on the surface. Reflectances are
often used for lighting calculations.
Describes rays of light bouncing off of multiple
surfaces within a room.
A device used to redirect the light output from a
source, primarily by bending the waves of light.
Glare resulting from reflections of bright objects
on polished or glossy surfaces. Also called
Veiling Reflection.
Semi-Direct
Semi-Indirect
Semi-Specular
Specular
Translucent
Transmission
Transparent
Veiling Reflection
A light distribution pattern or luminaire in which
40% or less of the light is directed downward and
60% or more of the light is directed upward.
A light distribution pattern or luminaire in which 60%
or more of the light is directed downward and 40%
or less of the light is directed upward.
Describes a mirrored or polished surface. The
angle of reflection is equal to the angle of
incidence. This word describes the finish of the
material used in some louvers and reflectors.
A term describing the light reflection characteristics
of a material. Light is reflected directionally, with
some amount of scatter.
The percentage of light that passes through a
translucent or diffusing material.
Describes a material that diffuses light passing
through it so that objects cannot be seen clearly
through it.
A glare reflection from a specular surface that
partially or completely obscures the object being
observes. Examples include reflection of a
luminaire on a glossy magazine page.
Describes a material with no diffusion of the light
passing through it so that objects are clearly seen
through it.